Conventionally, a lyophilized product, for example, is dissolved before use, and then, is given to a person. However, some lyophilized products are unstable since they are liable to be dissolved in water, oxygen or the like, or have bubbles which are hardly dissipated during dissolution. The lyophilized products such as an antibiotic, a growth hormone or a vaccine are stably stored or generally stored in a vial under a reduced pressure lower than an atmospheric pressure in order to prevent any generation of bubbles during the dissolution. However, in the case where the lyophilized product is stored in the vial, a dissolved liquid medicine need be transferred into a syringe, and therefore, it cannot be used at once. Otherwise, in the case where the liquid medicine obtained by dissolving the lyophilized product has a high viscosity, the syringe hardly sucks up the liquid medicine.
To deal with the above mentioned problem, as shown in FIG. 18 (see Patent Document 1), the inventors of the present application have developed a pressure reducing syringe 102 capable of storing a lyophilized product M therein under a reduced pressure by utilizing a sealed rubber plug 100 with a flange and a piston (i.e., a gasket) 101 having an air-liquid relief groove. In using the pressure reducing syringe 102 shown in FIG. 18, an outside syringe 105 having a syringe needle 103 attached thereto is prepared independently of the pressure reducing syringe 102. In this state, the syringe needle 103 of the outside syringe 105 pierces a rubber plug 108 of a vial 107 containing an attached solvent L therein. And then, a tip rubber packing 112 fixed to the pressure reducing syringe 102 is unsealed by one end (i.e., an upper end) of the syringe needle 103 by inserting the pressure reducing syringe 102 into the outside syringe 105, as indicated by an arrow. Subsequently, the sealed rubber plug 100 of the pressure reducing syringe 102 is detached, and further, a push rod 111 is connected to the piston 101, as shown in FIG. 19. Finally, the attached solvent L is sucked up into the pressure reducing syringe 102, to be dissolved inside of the syringe 102.
Patent Document 1: Japanese Patent Application Laid-open No. 11-155951